NEC Electronics Launches Advanced PPmL Next-Generation Interface Technology for LCD Driver ICs

The greatest feature of this new technology is that it enables the number of wires to be halved compared to conventional PPmL technology. With conventional PPmL technology, the video data and clock signal were transmitted via separate wires, but this new technology can accomplish this using a single wire. This makes it possible to combine the video data and clock signal into a single wire, thus enabling driver chips to be mounted on thinner circuit boards, and making it easy to synchronize the I/O timing of video data and clock signals. This in turn makes it possible to make LCD televisions with slimmer form factors, reduced frame thickness, and lower development costs. It also makes it easy to drive the television at high speed (120 Hertz – called double-speed driving).

Users can utilize timing controller ICs and LCD driver ICs with this new technology to develop large-screen televisions with more attractive designs; reduce motion blur when displaying video; and reduce the cost of developing televisions with double-speed driving function[2], which are expected to gain popularity in the future.

With the start of terrestrial digital television broadcasts, the television market has been evolving recently toward larger screens and higher video resolution. In particular, LCD televisions require chips to drive the LCD as well as a timing controller chip to send video data to multiple driver chips without delay. With large-screen LCD televisions, however, the wiring connecting the timing controller chip with the driver chips grows quite long; this could push the size of the boards to the limits of manufacturing capabilities, which would make handling these connections via a conventional bus interface unfeasible.

Conventionally, this was remedied by either reducing the wiring distance by splitting up control using multiple timing controller chips, or by reducing the frequency by splitting the video into multiple regions, thereby reducing the amount of data per bus. This method, however, increases the number of components, which causes cost to increase.

NEC Electronics responded to this situation in April 2006 with the release of PPmL, a point-to-point interface technology that transmits display data between timing controller chips and driver chips in a one-to-one relationship. PPmL makes it possible to conduct high-speed transmission using a single timing controller chip, regardless of wiring distance or the number of driver chips. This technology also permits a system architecture with fewer components, helping to reduce the cost of developing large-screen LCD televisions. The new Advanced PPmL technology was developed to further reduce development costs, as well as to satisfy market needs for the development of large-screen televisions: improved design aesthetic and faster LCD driving speeds in order to reduce motion blur.

The new technology was made possible through the use of clock-embedded technology. Clock-embedded technology encodes and decodes data to superimpose clock signal on data when it is sent and received. It is widely used in such high-speed digital communications as PCI Express and Ethernet. However, LCD driver ICs are made with relatively slow transistors, and this technology was not feasible until now because a great deal of power was consumed during high-speed (Gigahertz-range) communication, and the encoding/decoding logic circuit was too complex. NEC Electronics solved these challenges by developing a dedicated process for LCD driver ICs that enables high-speed transistors to be manufactured at low cost, and by developing a circuit with power consumption and scale optimized for LCD driver ICs.

NEC Electronics believes Advanced PPmL is an ideal technology for large-screen, high-definition LCD televisions, and plans to introduce the technology in its own LCD driver chips, in addition to building partnerships with other companies that develop timing controller chips.